Production of metal carbonyls



Patented June 30, 1931 UNITED STATES PATENT OFFICE WILHELM GAUS, F LUDWIGSHAFEN-ON-TI-IE-RHINE, ALWIN MITTASCH, OF MANNHEIM, AND LEO SGHIIECHT, OF L'UDWIGSHAFEN-ON-THE-RI-IINE, GERMANY, ASSIGNORS TO I. G. FARBENINDUSTRIE AKTIENGESELLSCHAFT, 0F FRANKFORT- ON-THE-MAIN, GERMANY, A CORPORATION OF GERMANY PRODUCTION OF METAL CARBONYLS No Drawing. Application filed .Tune 29, 1929, Serial No. 374,938, and in Germany July 5, 1928.

The present invention relates to the production of metal carbonyls from materials containing metals capable of forming metal carbonyls.

When trying to produce iron carbonyl by the action of carbon monoxide on iron by methods by which nickel carbonyl is produced on a commercial scale, either no iron carbonyl v at all is obtained or the process proceeds in such a sluggish manner that the process cana not be carried out on a commercial scale. It has been found that the difliculties in the production of iron carbonyl are due to a thin I film of iron carbonyl deposited on the iron under treatment which prevents the carbon monoxide from coming into contact with the iron. The said film once formed firmly adheresto the iron and is only slowly removed from the iron when working with streaming carbon monoxide so that the latter passes through the interstices between the particles of iron coated with the said film without reacting with the iron. l/Ve have now observed that the said film is readily removed when the iron is suspended in a liquid which is kept in motion with respect to the iron.

Relying on the said observation we have found a new process of producing metal car- H bonyls which consists in acting on metals capable of forming carbonyls which term is to be understood as comprising also materials containing such metals suspended in or made into a paste with liquids inert against the said metals and capable of dissolving carbon monoxide, though only to a low degree, with carbon monoxide or gases containing the same the liquid and the metal being kept in motion against each other. Liquids which may be used according to the present invention comprise also solidsubstances which are molten at the temperatures at which the process is carried out. The beforedescribed process has the further advantage that the suspension or paste previously prepared can readily be introduced continuously into the apparatus, in which the process is performed, and similarly the residue can be removed in the same form and in the same manner. Moreover the apparatus for the production oii carbonyl is much simpler and safer in operation, slnce the added liquids and melts act as agents facilitating sliding and tightening of the apparatus, in particular when introducing and removing the solid materials.

The process is carried out with particular advantage under increased pressure for example 100, 200 and even more atmospheres as by raising the pressure the amount of dis solved carbon monoxide is correspondingly increased. The height or" the pressure is only limited by the resistibility oi the apparatus.

The mixing of the material which is capable of forming carbonyl with a liquid is particularly advantageous in the working up of pulverulent or finely granular substances since carbonyl can otherwise be obtained from these substances in a dry state and on a large scale only with difficulty in consequence of their fine distribution.

Paraffin oil, molten paraflin wax, hydrocarbons of a high boiling point, such as for example benzine, oils, and similar substances which have low vapour tension and great solvent power for carbon monoxide, or the carbonyls of the metals which are to be converted into carbonyls, are suitable inert liquids for the purpose of the present invention.

The motion of the liquid and the metals against each other can be efiected in any suitable manner, for example by introducing the carbon monoxide or gases containing the same into the suspension or paste in such a manner as to causea motion of the suspension or paste, for example by introducing the gas in fine CllSJllblltlOIl into the suspension or passing it therethrough, or by agitating or revolving the reaction vessel. The re action mixture may also be kept moving by means of stirring or like devices. Such devices may be operated by means of the gases supplied to the reaction vessel or the expanding gases leaving the reaction vessel. A motion of the suspending liquid may also be caused by heating different parts of the. reaction vessel at dift'erent temperatures or the material under treatment may be moved electromagnetically.

The carbon monoxide is not necessarily passed into the suspension or paste sepa- I rately, but it may also be dissolved in the 1iqhave a good dissolving action on carbon introductlon' of monoxide. A separate gaseous carbon monoxide into the reaction chamber can thus entirely be dispensed with in some cases.

By increasing the pressure under which the carbon monoxide is dissolved in the liquid, as well as by increasing the speed, of flow at which the solution of carbon monoxide is passed over the material containing the metal capable of forming carbonyl and, if desired, by raising the temperature, the yield of metal carbonyl obtained in a certain time in a reaction chamber of a given space can be considerably increased.

The process can advantageously be carried out in a continuous manner and in a circular system. For example, iron carbonyl saturated at ordinary temperature withcarbon monoxide, suitably under the pressure employed in the reaction in which material containing iron is suspended, is introduced continuously intothe reaction chamber and the iron carbonyl after the reaction, now poor in carbon monoxide; is removed from the reaction chamber together with the residue in the form of a paste. The material containing iron may also beintroduc'ed separately into the reaction vessel and acted upon with iron carbonyl saturated with carbon monoxide. All or part of the iron carbonyl after being separated from the residue, preferablyalso in a continuous manner, can then again be saturated with carbon monoxide for instance by a treatmentwith gaseous carbon monoxide or gases containing the same and reintroduced into the process. When working under pressure the whole circular process may be carried outwithout releasing the pressure, so that only so much carbon monoxide needs to be compressed as is used'up in the process.

It may sometimes be of advantage, for instance for whirling up the metal powder within the liquid in the reaction chamber, to introduce gaseous carbon monoxide or gases containing the same into the reaction chamber simultaneously with the'liquid or melt previously saturated with carbon monoxide.

The following examples will further illustrate how the said invention is carried out in practice, but the invention is not restricted to these examples. The parts are by weight.

. Ewample J 5 partsof reduced fine grained roasted pyrites are made into a paste, with 3 parts of paraffinoil, and are treated in intimate contact with streaming carbon monoxide, for about 3 hours at 200 centigrade and 200 atmospheres pressure. In this manner 80 per cent of the iron is'volatilized as} carbonyl, and can be easily separated from the small. quantity of vapour of pararlin oil carried along with it by fractional condensation or distillation. l V i i Example 2 I Reduced roasted pyrites placed in an autoclave and submergedin liquid iron carbonyl is treated withcarbon monoxide under a pressure of 180 atmospheres at 180 0., while shaking the autoclave and keepingthe pressure of carbon monoxide constantly at the said height. The iron contained in the initial material is converted after 2 hours to about 80 per cent into iron carbonyl.

E pample 3 Liquid iron carbonyl saturated at ordinary temperature with carbon monoxide under a pressure of 200 atmospheres is passed, under the same pressure at 17 5 centrigrade over pulverulent, reduced roasted pyrites. Slper cent of the iron is converted into iron carbonyl in 2 hours a speed of the carbonyl satu rated with carbon monoxide of 190 litres per hour and per kilogram ofiron;

Example 4 Benzine saturated at ordinary temperature with carbon monoxide under a pressure of 200 atmospheres is passed at 175 centrigrade over reduced roasted byritesunder the said pressure. The issuing benzine contains 1.7 per cent by weight of iron carbonyl. Any desired amount of iron carbonyl may be incorporated with the benzine by Varying the speed of the flow of the benzine,-if desired, by repeated passing of the benzine preferably in a circuit,'t\vith or without an additional current of carbon monoxide or gases containing the same. In the said simple ;manner any liquid fuel capable of dissolving carbon oxide, while keeping the said metal and the said liquid in motion against each other.

2. The process of producing metal carbonyl which comprises acting on a metal capable of forming metal carbonyl, in mixture with an inert liquid which is a solvent for {carbon monoxide, with a gas containing carbon monoxide under increased pressure, while keeping the said metal and the said liquid in motion against each other.

monox1de,w1th a gas containing carbon mon- 3. The process of producing metal carbonyl which comprises acting on a metal capable of forming metal carbonyl, in mixture with the carbonyl of said metal in the liquid state, with a gas containing carbon monoxide, while keeping the said metal and the said metal carbonyl in motion against each other.

4. The process of producing metal carbonyl which comprises acting on a metal capable of forming metal carbonyl, in mixture with the carbonyl of said metal in the liquid state, with a gas containing carbon monoxide under increased pressure, while keeping the said metal and the said metal carbonyl in motion against each other..

5. The process of producing metal carbonyl which comprises dissolving a gas containing carbon monoxide in a'liquid inert against a metal capable of forming metal carbonyl andacting with the said solution on the said metal, while keeping the said solution and the carbonyl in motion against each other.

6. The process of producing metal carbonyl which comprises dissolving a gas containing carbon monoxide under increased pressure in a liquid inert against a metal capable of forming metal carbonyl and acting with the said solution on the said metal, while keeping the said metal and the said liquid in motion against each other.

7. The process of producing metal carbonyl which comprises dissolving a gas containing carbon monoxide in a metal carbonyl in the liquid state and acting with the said solution on a metal capable of forming metal carbonyl, while keeping the said solution and the said metal in motion against each other.

8. The process of producing metal carbonyl which comprises dissolving a gas containing carbon monoxide under increased pressure in a metal carbonyl in the liquid state and acting with the said solution on a metal capable of forming metal carbonyl, while keeping the said solution and the said metal in motion against each other.

9. The process of producing metal carbonyl which comprises dissolving a gas containing carbon monoxide under increased pressure in a metal carbonyl in the liquid state and acting with the said solution on a metal capable of forming metal carbonyl under substantially the same pressure, while keeping the said solution and the said metal in motion against each other.

10. The process of producing iron carbonyl which comprises saturating iron carbonyl with carbon monoxide under a pressure of about 200 atmospheres and passing the said solution under substantially the same pressure over iron at elevated temperatures.

In testimony whereof we have hereunto set our hands.

WILHELM GAUS. ALWIN MITTASCH. LEO SCHLECHT. 

